The 3-1/2 inch (unfolded length) twelve gauge has been with us for some time by now, having
been introduced in 1988 by Mossberg in the Ulti-Mag. Now, over 25 years later,
you might think that there would be some general consensus as to its value, but
that isn't the case.

The 3-1/2
inch 12 gauge has a higher allowable maximum average pressure (MAP) according
to the SAAMI specification at 14,000 PSI, versus the 11,500 PSI of other twelve
gauge shells. Whether factory shells are actually loaded to that is unknown,
for most ammunition companies don't make that information available. The reason
for the 3-1/2 inch shell is an attempt to improve the killing power of poor-performing
(compared to their lead counterparts) steel loads.

It offers
increased payloads, as 1-1/4 oz. is a common 3 inch steel load and 1-1/2 oz. is
a common 3-1/2 inch steel load. Along with increased payloads, you naturally
get increased recoil. Another negative is that they tend to be obnoxiously
loud, a good technique for destroying your hearing and annoying your buddies.

Shotgun manufacturers tend to like 3-1/2 chambered guns, for they can sell you
a gun that costs no more to make for more dollars. Is there any advantage?
Well, comparing 1400 fps 1-1/4 oz. loads to 1500 fps 1-1/2 oz. steel loads,
there is. As is always the case, it varies by individual gun, choke and shell,
but you can get roughly the same pattern percentages with 3-1/2 inch shells as
you can with 3 inch steel shells.

The notion that the 1-1/2 oz. payload of the 3-1/2 inch shell is something wondrous
does not bear scrutiny, for 1-1/2 oz. 2-3/4 inch 12 gauge shells with lead shot
aren't unusual and my favorite turkey load is 1-1/2 ounces out of a 20 gauge,
albeit at modest velocity.

The negatives include excessive noise, violent recoil and a higher sticker price on
the gun. The 3-1/2 inch steel ammo is more expensive, as well. Flipside, it
does give you more payload in a steel shot shell and can be a marginally better
long range load, in the neighborhood of five yards or so. Not so with most lead
loads, where 3-1/2 shells generally pattern worse than than 3 inch shells.

The rest comes down to the individual gun. For 3-1/2 inch inertia guns, you
lose reliability on the extreme low end of things, although I personally hunt
with nothing lighter than 1 oz. loads. In several tests, 3-1/2 inch Maxus, Super Vinci and A400 guns all handled factory 1
oz. loads without issues.

The 3-1/2 autoloader also makes sense when that's the only way it is offered, as in the
Versa Max. The Versa Max action does nothing to compensate for
2-3/4 inch shells, but it does automatically block off three its seven ports
when using 3 inch unfolded shells. It is the softest shooting 12 gauge, when
shooting 3 inch shells, on the market. This is due to three factors: the
automatic port block off, its substantial eight pound weight and its extremely
thick recoil pad.

There are valid reasons why a 3-1/2 12 gauge makes some sense, but very few, and only
with comparatively few autoloading shotguns. The performance-minded individual
will avoid steel altogether, for there is no 3-1/2 inch shell that compares
with Tungsten Matrix and other higher density shot materials in normal length shells.